A power steering apparatus for automobiles having heretofore been known is the so-called electrohydraulic type wherein as in, for example, a "motor-driven power steering apparatus" disclosed in the official gazette of Japanese Patent Application Laid-Open No. 59-223561 laid open on Dec. 15, 1984, an oil pump is driven by a motor, and the hydraulic pressure thereof is utilized to assist in the control force of a steering wheel. Such an electro-hydraulic type power steering apparatus is so constructed that electric power to the motor is cut off in the overdischarge state of a battery. In a case where a car is running along, e.g., a curve especially at a high speed, the construction is attended with the risk that the steering wheel will work improperly to return to its neutral position for a moment. It has not been considered at all that the battery is prevented from falling into the overdischarge state while the power steering function is held satisfactory.
This is conspicuous especially in cars furnished with power steering apparatuses of the so-called motor-driven type which are intended to assist in the steering operation directly with motor power, and incurs such a drawback that headlamps darken due to the overdischarge.